A 6 year longitudinal study of accelerometer-measured physical activity and sedentary time in Swedish adults.

OBJECTIVES The aim of this study was to investigate changes over six years in physical activity and sedentary behavior assessed with accelerometry in a representative sample of Swedish adults. DESIGN A longitudinal study over six years. METHODS The cohort consisted of 1172 participants (46% males) in 2002 and 511 participants (46% males) in 2008, of which 478 (45% males) had valid data on both occasions. Mean (SD) age at baseline was 45 (15) years. To analyze changes over time, a mixed linear model for average intensity physical activity (counts/min) and time in sedentary behavior and light- and moderate- or higher-intensity physical activity was conducted, stratified for sex and age, and adjusted for BMI, education, self-rated health and Δ wear time. RESULTS Over a six year period no significant changes were seen in the total cohort for average intensity and time in moderate- or higher intensity physical activity. A significant decrease in average intensity physical activity was found for men (p=0.006) and those aged 60+ years at baseline (p<0.001). A significant increase (26 min/day) for sedentary time in the total cohort (p<0.001) and for time in moderate or higher intensity physical activity among women (p<0.001) and those aged 40-59 years at baseline (p=0.014) was found over the follow-up period. CONCLUSIONS The overall increase in sedentary time and decrease in average physical activity among men and the elderly are of concern, since they might result in an elevated risk of developing chronic diseases.